1. Field of the Invention
The present invention relates generally to methods for genetically altering the cells of higher plants. More particularly, the invention relates to a method for genetically transforming cells from rose plants.
The hybrid tea rose, Rosa hybrida, is one of the most popular of all cultivated plants. As with any valuable plant species, breeders have long been working to improve existing varieties and create new varieties using conventional cross-breeding techniques. Characteristics of particular interest include color, fragrance, morphology, herbicide resistance, pesticide resistance, environmental tolerance, vase life of the cut flower, and the like. While improvements and variations in most or all of these areas have been achieved, progress is slow because of the perennial nature of the plant and the high incidence of plant sterility caused by abnormal chromosome numbers. While rose tissue culture is now possible based on work described in co-pending application Ser. No. 542,841, referenced above, the natural genetic variation offered by tissue culture is random and still requires substantial effort to produce a particular genetic variation.
For these reasons, it would be desirable to use recombinant DNA technology to produce new rose cultivars in a controlled and predictable manner. It would be particularly desirable to be able to genetically transform individual rose plant cells to introduce a desired characteristic and to be able to regenerate viable somatic embryos and rose plantlets from the modified cells. Such methods should be capable of introducing preselected exogenous genes to the rose plant cell and should permit selection of transformed cells which are capable of expressing the gene. The method should produce regenerated rose plants which have stably incorporated the gene(s).
2. Description of the Background Art
Abstract A203 (Noriega et al.) in Abstracts VIIth International Congress on Plant Tissue and Cell Culture, Amsterdam, Jun. 24-29, 1990, reports preliminary results on the production of calli from rose (Rosa hybrida) leaves. The reported results correspond to work described in related application U.S. Ser. No. 542,841, now abandoned previously incorporated herein by reference.
Tissue culture methods involving Rosa hybrida and other rose species are described in Handbook of Plant Cell Culture, Ammirato et al. (eds.), Chapter 29, 716-743, McGraw-Hill (1990); Skirvin et al. (1979) Hort Sci., 14:608-610; Hasegawa (1979) Hort Sci., 14:610-612; Khosh-Khui et al. (1982) J. Hort Sci., 57:315-319; Valles (1987) Acta Horticulturae, 212:691-696; Lloyd et al. (1988) Euphytica, 37:31-36; Burger (1990) Plant Cell Tissue and Organ Culture, 21:147-152; Ishioka et al. (1990) Plant Cell, Tissue and Organ Culture, 22:197-199; Matthews et al. "A Protoplast to Plant System in Roses" 7th IAPTC Congress, Amsterdam; and de Wit et al. (1990) Plant Cell Reports, 9:456-458.
The susceptibility of certain Rosa species to infection and tumor induction by Agrobacterium tumefaciens is described in De Cleene et al. (1976) The Botanical Review, 42:389-466. The susceptibility of certain Rosa species to infection and hairy root induction by Agrobacterium rhizogenes is described in De Cleene et al. (1981) The Botanical Review, 47:147-194.
The transformation of embryogenic calli from Prunus persica (a member of the Rosaceae family) with Agrobacterium tumefaciens is reported in Scorza (1990) In Vitro Cell Dev. Biol., 26:829-834. No disclosure of transformed plant material beyond callus stage or of regeneration of whole plants is provided. The transformation of explant materials from other members of the Rosaceae family is described in James et al. (1989) Plant Cell Reports, 7:658-661, and Graham et al. (1990) Plant Cell, Tissue and Organ Culture, 20:35-39.
The transformation of crushed tobacco callus with wild-type (virulent) Agrobacterium tumefaciens resulting in crown gall formation is reported in Muller et al. (1984) Biochem. and Biophys. Res. Comm., 123:458-462.